1. Technical Field
This disclosure relates to a heat storage material composition, a heat storage device that uses the heat storage material composition, and a heat storage method that uses the heat storage material composition.
2. Description of the Related Art
In using thermal energy in domestic and industrial applications, excess amounts of energy is sometimes generated relative to the amount of thermal energy needed. Moreover, the time thermal energy is generated may not always be the time thermal energy is needed. In order to make effective use of thermal energy generated, thermal energy has been temporarily stored by using heat storage materials.
Sensible heat storage materials and latent heat storage materials are known as heat storage materials. Latent heat storage materials are a type of heat storage materials that utilize phase changes such as melting of matters. Latent heat storage materials have a heat storage density higher than that of sensible heat storage materials. Latent heat storage materials have an advantage in that thermal energy can be stably retrieved from the latent heat storage materials since the temperature at the time of phase change is constant. In the case where heat is stored by using latent heat storage materials, the latent heat storage materials are heated and enter a liquid state. Then the latent heat storage materials are kept warm so as to maintain the liquid state. The heat stored in the latent heat storage materials can be retrieved at a desirable timing by crystallizing (solidifying) the latent heat storage materials.
Sugar alcohols have relatively high latent heat of melting and are known to be substances that can efficiently store heat with a relatively small volume. Sugar alcohols are also safe substances that do not exhibit toxicity. Although sugar alcohols melt at a temperature (melting point) specific to a substance, they are known to remain un-solidified and remain in a fluidized state, i.e., a supercooled state, at a temperature lower than the melting point once they are melted. Accordingly, studies have been focused on heat storage by keeping sugar-alcohol-containing latent heat storage materials in a supercooled state after they are heated to be in a liquid state. In such a case, the heat stored in the latent heat storage materials can be retrieved by releasing the supercooled state of the sugar-alcohol-containing latent heat storage materials.
Japanese Unexamined Patent Application Publication No. 2011-153206 describes a heat storage material composition containing a sugar alcohol and a polyether-modified silicone. Incorporation of a polyether-modified silicone into a heat storage material composition prevents sugar alcohol molecules from bonding to each other and suppresses crystallization (solidification) of the sugar alcohol. As a result, the crystallization onset temperature of the heat storage material composition is decreased and supercooling can be accelerated. For example, the crystallization onset temperature of the heat storage material composition of Example 1 in Japanese Unexamined Patent Application Publication No. 2011-153206 is 48.0° C.